\\[-1.8ex] Soil Heterogeneity & $-$0.325 & $-$0.275 & $-$0.739$^{**}$ & $-$0.719$^{**}$ \\ 
  & (0.217) & (0.219) & (0.322) & (0.319) \\ 
\\[-1.8ex] 
Observations & 7,370 & 7,370 & 2,038 & 2,038 \\ 
R$^{2}$ & 0.457 & 0.478 & 0.181 & 0.186 \\ 
